U.S. patent application number 12/530379 was filed with the patent office on 2010-03-11 for system for 3d image projections and viewing.
This patent application is currently assigned to DOLBY LABORATORIES LICENSING CORPORATION. Invention is credited to Wilson Allen, Gary Gomes, Martin Richards.
Application Number | 20100060857 12/530379 |
Document ID | / |
Family ID | 39684445 |
Filed Date | 2010-03-11 |
United States Patent
Application |
20100060857 |
Kind Code |
A1 |
Richards; Martin ; et
al. |
March 11, 2010 |
SYSTEM FOR 3D IMAGE PROJECTIONS AND VIEWING
Abstract
Shaped glasses have curved surface lenses with spectrally
complementary filters disposed thereon. The filters curved surface
lenses are configured to compensate for wavelength shifts occurring
due to viewing angles and other sources. Complementary images are
projected for viewing through projection filters having passbands
that pre-shift to compensate for subsequent wavelength shifts. At
least one filter may have more than 3 primary passbands. For
example, two filters include a first filter having passbands of low
blue, high blue, low green, high green, and red, and a second
filter having passbands of blue, green, and red. The additional
passbands may be utilized to more closely match a color space and
white point of a projector in which the filters are used. The
shaped glasses and projection filters together may be utilized as a
system for projecting and viewing 3D images.
Inventors: |
Richards; Martin; (Redwood
City, CA) ; Allen; Wilson; (Mill Valley, CA) ;
Gomes; Gary; (Fremont, CA) |
Correspondence
Address: |
Dolby Laboratories Inc.
100 Potrero Avenue
San Francisco
CA
94103-4938
US
|
Assignee: |
DOLBY LABORATORIES LICENSING
CORPORATION
San Francisco
CA
|
Family ID: |
39684445 |
Appl. No.: |
12/530379 |
Filed: |
May 9, 2008 |
PCT Filed: |
May 9, 2008 |
PCT NO: |
PCT/US08/06007 |
371 Date: |
September 8, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60931320 |
May 21, 2007 |
|
|
|
Current U.S.
Class: |
353/7 ; 348/53;
348/E13.075; 359/464; 359/891 |
Current CPC
Class: |
H04N 13/334 20180501;
H04N 13/363 20180501; H04N 13/324 20180501; G02B 26/008 20130101;
G02B 30/00 20200101; G02B 30/23 20200101; G02B 30/34 20200101; G02B
5/285 20130101 |
Class at
Publication: |
353/7 ; 359/464;
359/891; 348/E13.075; 348/53 |
International
Class: |
G02B 5/20 20060101
G02B005/20; G02B 27/22 20060101 G02B027/22; G03B 21/00 20060101
G03B021/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 9, 2007 |
US |
11801574 |
May 18, 2007 |
US |
11804602 |
Claims
1. Viewing filters comprising spectrally complementary filters,
comprising: a first filter having a first passband configured to
pass only a first color of light, a second passband configured to
pass only a second color of light, and a further transmission
region configured to pass only a third color of light; and a second
filter having a first passband comprising the first color of light
and the second color of light, and a second passband comprising the
second color of light and the third color of light; wherein the
second filter blocks visible light having longer wavelengths than
those contained in the second passband of the second filter.
2. The viewing filters according to claim 1, wherein the second
filter has a further transmission region configured to pass only
the first color of light.
3. The viewing filters according to claim 1, wherein the first
color of light is blue, the second color of light is green, and the
third color of light is red.
4. The viewing filters according to claim 1, wherein the filters
comprise a non-flat substrate comprising a curved surface
configured to reduce a wavelength shift that occurs when viewing an
image at other than a normal angle through the filters.
5. The viewing filters according to claim 4, wherein the curved
surface comprises a radii of approximately 90 mm.
6. The viewing filters according to claim 1, wherein at least one
of the filters is configured to have at least one passband
configured to pass two spectrum adjacent colors that are separated
by a notchband.
7. 3D viewing glasses, comprising: a first filter disposed on a
first lens of the glasses, and a second filter that is spectrally
complementary to the first filter disposed on a second lens of the
glasses; wherein the spectrally complementary filters account for a
blue shift that occurs when viewing images at off-normal angles via
both of, a combination of guardbands between passbands of the first
filter and passbands of the second filter, and a curvature of the
lenses.
8. The viewing filters according to claim 7, wherein at least one
of the spectrally complementary filters comprises a single passband
configured to pass two different colors of light.
9. The viewing filters according to claim 7, wherein the spectrally
complementary filters comprise a first filter having a set of N
passbands configured to pass a set of more than N primary color
lightbands.
10. The viewing filters according to claim 7, wherein: the
spectrally complementary filters comprise a first filter comprising
a first set of passbands configured to pass a first set of primary
lightbands and a second filter comprising a second set of passbands
configured to pass a second set of primary lightbands, wherein the
first set of primary lightbands are mutually exclusive to the
second set of primary lightbands; at least one of the passbands
encompasses at least two of the primary lightbands; and the first
set of passbands and the second set of passbands are separated by
guard bands having a width calculated to maintain separation
between the primary lightbands when viewed through the viewing
filters and compensate for blue shift due to a viewing angle of the
primary lightbands through the viewing filters.
11. A filter comprising three mutually exclusive passbands of
visible light, a first passband configured to pass only a first
color of light, a second passband configured to pass two spectrum
adjacent colors of light comprising the first color of light and a
second color of light, and a third passband configured to pass two
spectrum adjacent colors of light comprising the second color of
light and a third color of light.
12. The filter according to claim 11, wherein the first color of
light is blue, the second color of light is green, and the third
color of light is red.
13. The filter according to claim 11, wherein at least one of the
spectrum adjacent colors of light are separated by a notch
band.
14. The filter according to claim 11, wherein the filter is
installed in a 3D projection system comprising a server that
performs color correction using the spectrum adjacent colors of
light.
15. The filter according to claim 11, wherein: the filter comprises
a first filter disposed on a first lens of a pair of 3D viewing
glasses, and a second filter that is spectrally complementary to
the first filter; the spectrally complementary filters account for
a blue shift that occurs when viewing images at off-normal angles
via both of, a combination of guardbands between passbands of the
first filter and passbands of the second filter, and a curvature of
the lenses; and the curvature of the lenses comprises a radius of
approximately 40 mm to 200 mm.
16. The filter according to claim 11, wherein the first passband
ranges from below approximately 430 nm to approximately 442 nm, the
second passband ranges from approximately 486 nm to approximately
528 nm, and the third passband ranges from approximately 571 nm to
approximately 624 nm.
17. A viewing system, comprising: glasses comprising a pair of left
and right spectrally complementary viewing filters disposed on the
glasses; and a display system configured to display spectrally
separated left and right images respectively configured to be
viewed through the left and right spectrally complementary viewing
filters; wherein the display system comprises a pair of left and
right spectrally complementary projection filters, and wherein at
least one light band that is blocked by one of the projection
filters is passed by the corresponding viewing filter.
18. A viewing system, comprising: glasses comprising a pair of left
and right spectrally complementary viewing filters disposed on the
glasses; and a display system configured to display spectrally
separated left and right images respectively configured to be
viewed through the left and right spectrally complementary viewing
filters; wherein at least one light band that the display system
does not display in any of the left images is passed by the left
viewing filters, and/or at least one light band that the display
system does not display in any of the right images is passed by the
right viewing filter.
19. A 3D viewing system comprising a first filter set comprising a
projection filter and a viewing filter, wherein the projection
filter has a different number of passbands than the viewing
filter.
20. The 3D viewing system according to claim 19, wherein the
bandwidths and number of passbands of each filter are not the
same.
21. The 3D viewing system according to claim 19, wherein the
viewing filter includes passbands that approximately encompass
passbands of the projection filter; and the passbands of the
projection filter are pre-blue-shifted compared to the passbands of
the viewing filter.
22. The 3D viewing system according to claim 19, wherein the
projection filter comprises at least one channel comprising at
least two passbands of light in adjacent colors separated by a
blocking notch.
23. The 3D viewing system according to claim 22, wherein the
viewing filters comprise passband channels approximately
encompassing the passbands of the projection filter including the
blocking notch such that if the blocking notch were not present
light passing the projection filter in the wavelengths of the
blocking notch would also pass through the viewing glasses.
24. A filter system, comprising: a projection filter, comprising, a
set of first channel passbands and a set of second channel
passbands configured to pass light, a set of guard bands configured
to block light between adjacent passbands of different channels,
and at least one notchband between adjacent colors of a same
channel passband configured to block light between the adjacent
colors.
25. The filter system according to claim 24, further comprising a
set of viewing filters including a first channel viewing filter and
a second channel viewing filter, wherein the viewing filter
corresponding to the channel of the notchband passes light
wavelengths corresponding to the notchband.
26. The filter system according to claim 24, wherein the at least
one notchband comprises at least two notchbands comprising a
blue-green notchband and a green-red notchband.
27. The filter system according to claim 24, wherein the first set
of channel passbands has a different number of primary passbands
than the second set of channel passbands.
28. The filter system according to claim 24, wherein the first
channel passbands comprise wavelengths of approximately 400 to 440
nm, 484 to 498 nm, 514 to 528 nm, 567 to 581 nm, and 610 to 623
nm.
29. The filter system according to claim 24, wherein the second
channel passbands comprise wavelengths of approximately 455 to 471
nm, 539 to 556 nm, and 634 to 700 nm.
Description
COPYRIGHT NOTICE
[0001] A portion of the disclosure of this patent document contains
material which is subject to copyright protection. The copyright
owner has no objection to the facsimile reproduction by anyone of
the patent document or the patent disclosure, as it appears in the
Patent and Trademark Office patent file or records, but otherwise
reserves all copyright rights whatsoever.
TECHNICAL FIELD
[0002] The present invention relates viewing systems and products
for projecting and viewing spectrally separated 3-Dimensional (3D)
images. The invention is also related to viewing systems used in a
Digital Cinema (D-Cinema) Theatre and improves current methods for
projecting and viewing a 3D stereoscopic movie.
BACKGROUND ART
[0003] Methods for 3D stereoscopic projection include Anaglyph,
Linear Polarization, Circular Polarization, Shutter Glasses, and
Spectral Separation. Anaglyph is the oldest technology, and
provides left/right eye separation by filtering the light through a
two color filter, commonly red for one eye, and cyan for the other
eye. At the projector, the left eye image is (commonly) filtered
through a red filter, and the right image filtered through a cyan
filter. The eyewear includes, for example, a red filter for the
left eye, and a cyan filter for the right eye. This method works
best for black and white original images, and is not well suited
for color images.
[0004] Linear Polarization 3D provides separation at the projector
by filtering the left eye through a linear polarizer (commonly)
oriented vertically, and filtering the right eye image through a
linear polarizer oriented horizontally. The eyewear includes a
vertically oriented linear polarizer for the left eye and a
horizontally oriented polarizer for the right eye. The projection
screen must be of the polarization preserving type, commonly
referred to as a "silver screen" because of its distinctive color.
Linear Polarization allows a full color image to be displayed with
little color distortion. It has several problems, these include the
need for a silver screen which is expensive, fragile, and not
uniform. Another problem is that the viewer must keep his head
oriented vertically to avoid crosstalk from one eye to another.
[0005] Circular Polarization 3D was invented to address the problem
of requiring the viewer to keep his head oriented vertically.
Circular Polarization provides separation at the projector by
filtering the left eye image through a (commonly) left handed
circular polarizer, and filtering the right eye image through a
right handed circular polarizer. The eyewear includes a left handed
circular polarizer for the left eye and a right handed circular
polarizer for the right eye. A silver screen is also needed for
this approach.
[0006] Shutter Glasses provides separation by multiplexing the left
and right images in time. A filter for separation at the projector
is not required. The eyewear includes Shutter Glasses. These are
active glasses that electronically shutter the lens in synchrony
with the projector frame rate. The left eye image is first
displayed, followed by the right eye image etc. Since having a
direct wired connection to the Glasses in a theatre is impractical,
a wireless or infrared signaling method is used to provide a timing
reference for the left/right eye shuttering. This method requires
an IR or RF transmitter in the auditorium. The Shutter Glasses are
expensive and hard to clean, require batteries that must be
frequently replaced, and are limited in their switching rate.
Shutter glasses are only practical for use with D-Cinema or other
electronic projection systems since very few film projectors
provide the signal required to synchronize the shutter glasses with
the frame rate. The method does not require a silver screen.
[0007] Spectral Separation provides separation at the projector by
filtering the left and right eye spectrally. The system differs
from anaglyph in that the filters for the left and right eye each
pass a portion of the red, green, and blue spectrum, providing for
a full color image. The band pass spectrum of the left eye filter
is complementary to the band pass spectrum of the right eye filter.
The eyewear includes filters with the same general spectral
characteristics as are used in the projector. While this method
provides a full color image, it requires color compensation to make
the colors in the left and right eye match the colors that were
present in the original image, and there is a small reduction in
the color gamut compared to the gamut of the projector.
[0008] All of the above methods for providing left/right eye
separation for a 3D Stereoscopic presentation can be used with
either two projectors (one for the left eye and one for the right
eye), or may be used with a single D-Cinema projector system. In
the dual projection system, the projection filter is usually
static, and is located in front of the projection lens. In a single
D-Cinema projector system, the left and right images are time
multiplexed. Except for the Shutter Glasses case where no
projection filters are required, this means that the projection
filters must change at the L/R multiplex frequency. This can be
done with either a filter wheel in the projector synchronized to
the multiplex frequency, or with an electronically switched
filter.
DISCLOSURE OF THE INVENTION
[0009] The present inventors have realized the need for
improvements in spectrally separated viewing devices and systems.
The invention provides several techniques to remove and compensate
for blue shift that occurs when viewing images through filters at
off-axis (other than normal) angles. The blue shift is undesirable
because it can result in crosstalk between left and right images in
a 3D image presentation.
[0010] The present inventors have also realized the need for
improvements in spectral separation filters, and particularly those
used in 3D D-Cinema applications. One problem realized is that
typical 3-D projection systems have low luminance efficiency in
that color spaces, color gamut, and effective brightness are
inadequate. Another problem realized is that imbalance between
luminance levels in channels of 3D projections decreases luminal
efficiency. Accordingly, as described in more detail below, the
present invention also provides techniques to increase the color
space and luminal efficiency of projected images that may be used
alone or in combination with blue shift compensation
techniques.
[0011] The present invention includes one or more techniques to
increase the color space of spectrally separated images which may
be combined with one or more techniques to compensate for blue
shift that occurs when viewing spectrally separated images through
filters at other than normal angles. The individual techniques are
further described herein. When utilized together, the invention is
a system comprising a 3D projection device using asymmetric
projection filters and viewing glasses comprising non-flat lenses
with spectrally complimentary filters.
[0012] Generally described, in one embodiment, the present
invention provides a pair of 3D spectral separation filters (eye
filters), disposed on left and right lenses of a pair of viewing
glasses, the eye filters comprising a combination of increased (and
proportional to wavelength) guard bands, and appropriately curved
lenses to reduce crosstalk, color shift, and reflections at the
edge of the field of view. A blue shifted color filter in a
projector that projects images for viewing through the glasses may
also be utilized. Although the present invention encompasses a
combination of improvements to viewing glasses and preparation of
images for viewing (e.g., image projection), the invention may be
practiced with less than all the improvements in combination.
[0013] In one embodiment, the present invention comprises viewing
filters comprising a non-flat substrate and spectrally
complementary filters.
[0014] In one embodiment, the present invention provides spectral
separation viewing glasses, comprising, a first lens having a first
spectral filter, and a second lens having a second spectral filter
complementary to the first spectral filter, wherein the first lens
and the second lens are each curved to reduce the wavelength shift
that occurs when viewing an image at other than an angle normal to
a filter through which the image is being viewed. An amount of
curvature of the lenses (and hence the filters) is calculated such
that viewing angles across a viewing screen are closer to normal
angles through the lenses. The curvature is implemented, for
example, as a spherical curve.
[0015] In another embodiment, the invention is embodied as spectral
separation viewing glasses, comprising, a first lens comprising a
first spectral filter, and a second lens comprising a second
spectral filter complementary to the first spectral filter, wherein
the first spectral filter and the second spectral filter have at
least one guard band between adjacent portions of spectrum of the
spectral filters. The guard band has a bandwidth sufficient to
remove crosstalk of spectrally separated images viewed through the
glasses, and, for example, is calculated based on an amount of
wavelength shift occurring when viewing portions of the spectrally
separated images at an angle through the filters.
[0016] In one embodiment, the present invention provides a spectral
separation viewing system, comprising, viewing glasses having both
curved lenses and increased guard bands, and a projection system
configured to project first and second spectrally separated images
wherein the images are wavelength pre-shifted to compensate for
wavelength shifts occurring during display and/or viewing of the
images. Such systems are preferably implemented in a commercial
movie theater, but are also applicable to large screen televisions,
computers, virtual reality systems, and other display devices.
[0017] The present invention includes a method, comprising the
steps of, projecting first and second spectrally separated images
onto a display screen, viewing the projected images through a pair
of glasses having a first lens having a first spectral filter
matching the first spectrally separated image and a second lens
having a second spectral filter matching the second spectrally
separated image, wherein the spectral filters are configured to
have a varying amount of wavelength shift effect depending upon a
viewing angle through the lens.
[0018] In one embodiment, the present invention is a 3D viewing
system, comprising, means for projecting spectrally separated
images, means for viewing the spectrally separated images through
different ocular channels, and means for compensating for
wavelength shifts occurring due to viewing angles to portions of
the images. The means for compensating may include, for example,
means for adjusting an amount of spectral filtering performed on
different portions of the image based on viewing angle. The means
for compensating includes, for example, means for producing a
wavelength mismatch between projector filters and eye filters that
compensates for an amount of wavelength shift that occurs in the
eye filters due to viewing angle.
[0019] The present invention may also be described as shaped
glasses, comprising a pair of spectrally complementary filters
disposed on curved lenses of the glasses. The spectrally
complementary filters may include guard bands between adjacent
spectrums of the spectrally complementary filters. In one
embodiment, the thickness of dielectric layers of the spectrally
complementary filters increases toward edges of the lenses.
[0020] The present invention includes a method, comprising the
steps of, distributing shaped glasses to audience viewers, and
projecting first and second spectrally complementary images on a
display screen within view of the audience members, wherein the
shaped glasses comprise first and second shaped lenses having first
and second spectrally complementary filters respectively disposed
thereon. In one embodiment, the first and second spectrally
complementary filters respectively correspond in bandwidth to the
projected first and second spectrally complementary images.
However, the filters are not necessarily required to correspond
exactly with the projected images of the filters. The shaped
glasses comprise, for example, spherically shaped lenses.
[0021] The present invention includes a storage medium having at
least a visual performance stored thereon, that, when loaded into a
media player coupled to a display device, causes the media player
to transmit the visual performance for display to the display
device; wherein the visual performance as displayed on the display
device is configured for viewing through a pair of shaped glasses.
The storage medium is, for example, prepackaged with at least one
pair of shaped glasses and available for purchase via a retail
outlet.
[0022] In yet another embodiment, the present invention is a system
for viewing 3D images, comprising, serving 3D content over a
network to a receiving electronic device, and displaying the 3D
content, wherein the 3D content comprises spectrally complementary
images intended to be viewed with spectrally separated shaped
glasses. The receiving electronic device is, for example, a display
system located at a movie theater.
[0023] The present invention addresses some of the problems with
the Spectral Separation method for projecting 3D images,
specifically an improvement in the efficiency, increase in the
color gamut, and a reduction in the amount of color compensation
required. In some cases, the color compensation may not be
required. The present invention addresses the efficiency and color
space issues by splitting primary colors of the projector into
subparts. The splitting of primary colors into subparts is
accomplished in part through the filter installed in the projector,
which is the main controlling factor in the color space of the
system. The efficiency and color gamut of the projected image are
both increased using the additional subparts of the split primary
colors.
[0024] In one embodiment, the present invention provides a
projector filter, comprising, a first filter having a first set of
primary passbands, and a second filter having a second set of
primary passbands, wherein the first set of primary passbands has a
different number of primary passbands than the second filter. The
first filter has, for example, at least two blue primary passbands
and the second filter has at least one blue primary passband. The
first filter may also have, for example, at least two green primary
passbands and the second filter has at least one green primary. For
example, the first filter may have passband wavelengths of
approximately 400 to 440 nm and 484 to 498 nm, 514 to 528 nm, 567
to 581 nm, and 610 to 623 nm, and the second filter may have
passband wavelengths of approximately 455 to 471 nm, 539 to 556 nm,
and 634 to 700 nm. The passbands of the first filter and the second
filter are, for example, selected to maximize reproduction of a
color space of a D-Cinema projector.
[0025] The present invention may also be realized as a system for
projection of spectrally separated 3D images, comprising, a
projection system configured to project left and right channel
images for display by a viewer, a filter placed in at least one
light path of the projection system comprising a left channel
filter and a right channel filter, wherein at least one of the left
and right channel filters has more than 3 primary passbands. In one
embodiment, one of the left and right channel filters has at least
2 primary passbands in blue wavelengths and one of the left and
right channel filters has at least 2 primary passbands in green
wavelengths. Again, the primary passbands of the filters are
selected to maximize reproduction of a color space of the
projection system in images projected by the projection system. The
system may include, for example, a color correction module
configured to color correct images projected by the projection
system according to a color space of the filters.
[0026] The invention may also be embodied as a set of filters,
comprising a first filter having a first set of primary color
passbands, a second filter having a second set of primary color
passbands of different wavelengths compared to the first set of
primary colors, wherein the first filter has more than one primary
color in at least one color band.
[0027] The present invention may also be embodied as a method,
comprising the steps of, preparing a 3D image comprising a left
image and a right image, filtering the left image with a left
channel filter, filtering the right image with a right channel
filter, and projecting the left and right filtered images onto a
screen, wherein at least one of the left channel filter and right
channel filter have more than 3 primary passbands. As in all of the
above described embodiments, the filters (e.g., filters used in
performing the steps of filtering) may themselves be embodied in an
electronically switchable filter set, fixed filters in a two
projector system, or a filter wheel wherein approximately 1/2 the
wheel has filter characteristics of a left channel filter according
to the present invention and approximately 1/2 the wheel has filter
characteristics of a right channel filter according to the present
invention.
[0028] Portions of the invention may be conveniently implemented in
programming on a general purpose computer, or networked computers,
and the results may be displayed on an output device connected to
any of the general purpose, networked computers, or transmitted to
a remote device for output or display. In particular, the invention
includes the utilization of software that implements color
processing separately on each ocular channel. Any components of the
present invention represented in a computer program, data
sequences, and/or control signals may be embodied as an electronic
signal broadcast (or transmitted) at any frequency in any medium
including, but not limited to, wireless broadcasts, and
transmissions over copper wire(s), fiber optic cable(s), and
co-axial cable(s), etc.
DESCRIPTION OF THE DRAWINGS
[0029] A more complete appreciation of the invention and many of
the attendant advantages thereof will be readily obtained as the
same becomes better understood by reference to the following
detailed description when considered in connection with the
accompanying drawings, wherein:
[0030] FIG. 1A is an illustration of viewing angles;
[0031] FIG. 1B is graph illustrating spectrum of left projector
filter and right eye filter;
[0032] FIG. 2 is a graph illustrating spectrum of left projector
filter vs. blue shifted right eye filter;
[0033] FIG. 3 is a graph illustrating spectrum of blue shifted left
projector filter vs. blue shifted right eye filter;
[0034] FIG. 4A is a diagram illustrating geometry of curved lenses
centered at a viewer's pupil;
[0035] FIG. 4B is an illustration of glasses with spherical
lenses;
[0036] FIG. 5 is a diagram illustrating geometry of curved lenses
and showing child interpupillary distances;
[0037] FIG. 6 is a diagram illustrating geometry of curved lenses
for 20 degree angle at an edge of the lenses;
[0038] FIG. 7 is a diagram illustrating geometry of curved lenses
with non-spherical curve;
[0039] FIG. 8A is a diagram illustrating effect of lens curvature
on light coming from behind a viewer;
[0040] FIG. 8B is a drawing of dihedral angles for a pair of
viewing glasses.
[0041] FIG. 9 is a drawing illustrating glass frames configured for
use on different sized heads.
[0042] FIG. 10 is a diagram illustrating geometry of optimized
dihedral glasses.
[0043] FIG. 11 is a graph of conventional left and right spectral
separation filters.
[0044] FIG. 12 is a 1931 CIE chromaticity diagram illustrating the
color space of a typical Digital Cinema (D-Cinema) projector.
[0045] FIG. 13 is a 1931 CIE chromaticity diagram illustrating the
color space of conventional spectral separation filters.
[0046] FIG. 14 is a graph of left and right projector filters.
[0047] FIG. 15 is a 1931 CIE chromaticity diagram illustrating the
color space of color filters.
[0048] FIG. 16 is a graph of left and right eyeglass filters that
may be applied in conjunction with the projector filters described
in FIG. 4.
[0049] FIG. 17A is a block diagram of a projection.
[0050] FIG. 17B is a drawing of a filter wheel; and
[0051] FIG. 18 is a drawing of a fixed filter arrangement in a two
projector system.
BEST MODE FOR CARRYING OUT THE INVENTION
[0052] This invention addresses some of the problems with the
Spectral Separation method for projecting 3D images, specifically
this invention aims to improve the off-axis filter characteristics
when thin film dielectric (interference) filters (e.g., right eye
and left eye filters) are used to implement eyewear (e.g., glasses)
for viewing spectrally separated images.
[0053] When light passes through an interference filter at a
non-normal angle, the filter characteristics (response shapes, not
to be confused with the physical shape of the filter) are changed,
and the entire spectral filter response is shifted toward shorter
wavelengths (toward the blue). The filter characteristic response
shapes are also adversely affected at larger angles. This is a
fundamental attribute of interference filters, and can be
compensated for by designing the filter for a specific angle if all
of the rays are parallel. In cases where the light bundle is not
parallel, as in the case with the use of 3-D glasses, solutions
involving only design of the filter characteristics are less
practical.
[0054] Glasses currently used for spectral separation consist of
flat interference filters located about 2 cm in front of the
viewer's eyes. In a 3D Cinema theatre (e.g., 3D D-Cinema) the light
from the screen does not pass through the interference filters at a
single angle. For a viewer located center and one screen width
back, when viewing the image at the center of the screen, the light
from the center of the screen would pass through the interference
filters of the glasses at a normal (perpendicular) angle (assuming
the viewer's head is positioned such that the plane of the
interference filters is parallel to the plane of the screen). Under
similar conditions, light from the edge of the screen would pass
through the interference filters at an angle of about 26
degrees.
[0055] This viewing position is reasonably close to the screen, but
is not abnormal; many of the seats in a common auditorium are
located closer, and angles of 40 degrees are possible. A 26 degree
angle from the edge of the screen would have the effect of shifting
the filter response toward the blue by about 14 nanometers (nm),
and would somewhat distort the filter shape. The resulting 3D image
appears to have noticeable color shift and increased left/right eye
crosstalk towards the edges of the screen.
[0056] The invention uses a combination of several techniques to
reduce the effects of the blue shift, and to reduce the blue shift
occurring from non-normal viewing angles. It should be remembered
that the blue shift at the interference filters (e.g., lenses of
the glasses having filters disposed thereon) is primarily important
because it causes a mismatch between spectral characteristics of
the projector filter (e.g., a filter wheel or electronically
switched filter) and the glasses, or more precisely, a mismatch
between the spectra of light forming the images (from whatever
source) and the characteristics of the glasses at a given viewing
angle.
[0057] Referring now to the drawings, wherein like reference
numerals designate identical or corresponding parts, and more
particularly to FIG. 1A thereof, there are illustrated example
viewing angles through glasses 1110 for a viewer 1100 of an image
projected onto a movie screen 1120. The viewing angles range from
normal to somewhat oblique (e.g., approximately .theta..sub.1 to
.theta..sub.3, respectively). The glasses 1110 include lenses with
dielectric based interference filters. The non-normal viewing
angles have an amount of blue-shift associated with the viewed
image that increases with greater obliqueness of the viewing angle
through the interference filters. For example, light entering the
user's eyes from the more oblique angles .theta..sub.2 and
.theta..sub.3 will be shifted toward blue wavelengths whereas the
more normal angle .theta..sub.1 will have little, if any, blue
shift. The blue shift, or wavelength shift, so described results
from a shift in the interference filter properties such that the
light bands passed by the filter are shifted toward shorter
wavelengths.
[0058] One effect of the blue shift of light viewed at the edge of
the screen (e.g., light 1130) is to introduce crosstalk in the
image. This can be reduced by increasing the guard bands between
left eye and right eye filter characteristics. FIG. 1B illustrates
characteristics of exemplary filters used for 3D spectral
separation. As shown in FIG. 1B, bandwidths for a left projection
filter 100, and a right eye filter 110, includes guard bands 120,
122, 124, 126, and 128 which appear as notches between adjacent
light bands (FIG. 1B illustrates the right eye filter and the left
projection filter; the right eye filter approximately represents
bandwidths of the right projection filter and the left projection
filter approximately represents bandwidths of the left eye filter).
By increasing the width of the notch (or guard band) between left
and right spectra in both the eye filters and the corresponding
projector filters, crosstalk can be reduced. This also reduces the
perceived color shift. This method also reduces the optical
efficiency of the system, but this tradeoff may be made.
[0059] As can be seen in FIG. 1B, as a pair, the left and right eye
filters are complementary in that the filter properties of the left
eye filter (approximately represented by the left projection filter
100) complement the filter properties of the right eye filter 110.
It is not a full complement in that the guard bands keep the
combined filters from passing the entire portion of the spectrum
between the longest and shortest wavelengths passed by the filters.
Further, additional differences in bandwidth within the ranges of
the various bands passed by the filters may be made so as to
accommodate engineering decisions regarding color space issues that
need to be addressed for a particular application.
[0060] Another approach is to pre-blue shift characteristics of the
projector filter, or red shift the eye filters, such that for
viewing at a normal angle of incidence through the eye filters, the
filter characteristics are red shifted with respect to the
projector filter. This increases the crosstalk and color shift for
normal (on axis) viewing, but this can be tuned such that for on
axis viewing the crosstalk and color shift is not objectionable.
For the off axis case, the performance is improved since the
difference between the projector filters and the blue shifted
(off-axis) eye filters is lower.
[0061] FIG. 2 and FIG. 3 describe this situation. As shown in FIG.
2, a left projector filter 200, and a blue shifted right eye filter
210 have guard bands including guard band 220 separating adjacent
bands of light). As shown in FIG. 3, a blue shifted left projector
filter 300 and a blue shifted right eye filter 310 have guard bands
including guard band 320 separating adjacent bands of light. As
seen by comparing FIG. 2 and FIG. 3, the notch (guard bands 210 and
310) separating the adjacent bands of light is larger in FIG.
3.
[0062] Applying this to the case described earlier, the shift of 14
nm at the edges of the screen could be reduced to an effective
shift of 11 nm if the projector filter were shifted blue 3 nm.
There would be a "red shift" of 3 nm at the center of the
screen.
[0063] Another approach is to curve the filters, which can be
implemented, for example, by disposing the eye filters on curved
lenses of viewing glasses. This has the advantage that it has the
potential of actually reducing the blue shift.
[0064] FIG. 4A describes the geometry of curved lenses with a
radius centered at the eye pupil. The lenses shown (lens 405A
having optical axis 410A and lens 405B having optical axis 410B)
have a width of 50 mm and the chord is located 20 mm from a
respective pupil (and center of curvature) (e.g., 400A and 400B).
The measurements were made for the inventor's eyes, but are
representative of the general situation that could be implemented
for anyone wearing 3D glasses. Using glasses with lenses having a
spherical section with a radius centered on the entrance pupil of
the eye virtually eliminates any blue shift in the filters because
the light passes through the lenses (and hence, the filters)
virtually normal to the lens/filter for viewing all parts of the
screen. Some distortion occurs when the viewer turns his eyes to
look at different parts of the screen, but for the geometry shown,
this is not significant. FIG. 4B illustrates two views of a pair of
glasses 490 having curved lenses 492A and 492B which are both
spherically shaped and having spectrally complementary dielectric
filters disposed thereon (left eye filter 496A and right eye filter
496B).
[0065] The curvatures of the lenses so implemented are
distinguished from prescription glasses in that the implemented
curvatures are not to correct vision. Nevertheless, in one
embodiment, the curvature of the invention may be implemented over
or in addition to other lens characteristics intended to fulfill a
viewer's prescription needs.
[0066] The curved lens solution still has some limitations. First,
the radius of curvature of 30 mm resulting from the geometry
described above appears very "bug-eyed," and would be esthetically
unpleasing. Second, this curvature would produce glasses whose
weight would be centered well in front of the nosepiece, and they
would be poorly balanced. Third, this radius may be too short to
allow uniform coating of an interference filter.
[0067] Fourth, the interpupillary distance of eyes varies
significantly, and this would mean that glasses designed for the
mean would be improperly curved for someone with other than the
mean distance. For example, with a child the situation may result
in an angle of about 10 degrees for viewing of the center of the
screen. As shown in FIG. 5, the location of a child's pupils (510A
and 510B) and the resulting optical axis of the child's eye (530A
and 530B) is displaced off the corresponding optical axis of the
glasses (520A and 520B respectively centered at center of
curvatures 500A and 500B).
[0068] Even considering the limitations associated with curving the
lenses and/or filters, this technique is valuable. Although in
general cases or productions for mass audiences, it may not make
sense to attempt to have the radius of curvature centered directly
at the entrance pupil of the eye. By making the lenses spherical
but with a radius of curvature centered behind the entrance of the
pupil of the eye, much of the problems are removed (e.g., bringing
the center of gravity back toward the viewer, and a less "bug-eyed"
appearance) and the advantages are significantly retained.
[0069] In one alternative, the lenses may use a non-spherical
curvature, such as a cylindrical curvature where the lenses are
only curved from left to right, and there is no curvature in the
vertical direction. This is possible because the screens always
have an aspect ratio such that the horizontal extent (e.g., width)
is about twice the vertical extent (e.g., height). Another
alternative is to use a curvature that is non spherical in either
direction, such as a multiple radius surface, or one that follows a
specific mathematical function. These have advantages for allowing
a greater interpupillary variation. An additional advantage of
curved lenses includes the reduction of reflections from bright
surfaces behind the viewer, since these reflections are not
directed toward the eye.
[0070] A final approach involves the design of the interference
filters. This approach requires changing the thickness of the
dielectric layers as a function of the distance from the center of
each eye filter. If the thicknesses of the dielectric layers are
increased at the edges of the filters such that they cause a red
shift in the filter characteristics, this can be used to compensate
for the blue shift caused by the angle change at the edges of the
field of view through the filters.
[0071] If the filters are implemented on flat glass, the thickening
of the dielectric layers may increase manufacturing costs due to
difficulty in implementing the increased thicknesses at different
points on the flat glass. However, when coating on a curved
surface, some thickening occurs during the coating process. This
approach therefore becomes a practical adjunct to the curved lens
solution.
[0072] The best method for achieving high performance with
interference filters incorporates the four techniques described
above in the following manner. First, the guard bands between left
and right eye filters should be greater than approximately 2%
(e.g., 2.2%) of the wavelength of that filter band. For example,
for a filter with a left/right crossover at 640 nm, the guard band
should be approximately 14 nm. Second, the projector filter should
be designed to be blue shifted (with respect to the eye glass
filters) greater than 0.6% of the wavelength of the filter band. In
the same example, the center of the guard band for the projector
filter would be 640-3.8=636.2 nm. The combination of these allow
nominally manufactured lenses and eye filters (when used with a
nominally manufactured projector lens and projector filters) to be
tilted such that a blue shift of 18 nm occurs before serious
degradation of the image occurs.
[0073] However, the combined manufacturing tolerance from the
projector filters and the eye filters reduces this to about 9 nm.
The 9 nm guard band that remains can be used for accommodating the
blue shift caused by the light going through the left and right eye
filters at an angle. The angle through the left and right eye
filters that causes a 9 nm shift is about 20 degrees. If the
curvature of the eye filters (e.g., curvature of lenses upon which
the eye filters are disposed or incorporated) is adjusted to allow
the light from the edge of the eye filters to pass through to the
eye at a maximum of 20 degrees relative to the normal of the eye
filters at the edge, then serious degradation of the image at the
edge of the eye filters will not occur.
[0074] For a simple sphere, and with the eye looking straight at
the center of the screen (e.g., a primary gaze normal to a tangent
of the lens), the radius of curvature needed to achieve this is
approximately 50 mm. As shown in FIG. 6 (lenses 605A and 605B have
respective centers of curvature 610A and 610B; adult pupil
locations at 615A, 615B and corresponding optical axis of the
lenses and adult eye 630A and 630B; child pupil locations at 620A,
620B and corresponding optical axis of child's eye 635A and 635B).
In practice the radius of curvature may be somewhat greater than 50
mm to accommodate the pupil shift when the eye is turned to observe
the side of the picture screen.
[0075] Although spherically shaped lenses are preferred,
non-spherical lenses do have some advantages. FIG. 7 shows left and
right lenses 705A and 705B with a non-spherical curve (adult pupils
700A, 700B; optical axis of the lenses 715A, 715B; child pupils
710A, 710B, and corresponding optical axis of child's eye 720A,
720B). The left and right lenses incorporate corresponding left and
right eye filters. The filters are, for example, disposed on one or
more surfaces of the lenses. The advantages of a non-spherical
curve are found in accommodating variations of interpupillary
distances between different viewers. Finally, a non-uniform
dielectric coating can be used to red shift the filter
characteristics at the edges of the filters, further improving the
performance.
[0076] A more important advantage is that reflections from behind
the viewer are reduced by the curvature. This is important because
the interference filters disposed on the eyeglass lenses reflect
light that is not transmitted, and are therefore quite reflective.
Without the curve, the audience behind the viewer is visible across
much of the back side of the lens. With the curve, only a portion
(or none) of the lens has a reflection from behind the viewer. FIG.
8 illustrates this advantage by comparison of a curved lens 705
having a center of curvature at 708 and a flat lens 710. With
respect to the flat lens 710, a relatively wide angled light ray
725 from behind the viewer is reflected off the flat lens into the
viewer's pupil 700A. With respect to the curved lens 705, it is
shown that only a relatively narrow angle (light ray 720) can reach
the viewer's pupil 700B via reflection from the curved lens. In
addition, the viewer's temple 730 blocks most light rays
sufficiently narrow to enter the viewer's temple.
[0077] Further optimization of the techniques discussed can be
achieved by accommodating interpupillary distance variation among
the population. In general, interpupillary spacing is directly
related to head width and girth. Adults have larger width and
girth, and wider interpupillary spacing, while children are smaller
in these dimensions. Ideally, a viewer would wear glasses with the
left and right eye filters disposed on corresponding left and right
lenses of the glasses where the interocular spacing of the lenses
is optimized for the viewer's particular interpupillary
distances.
[0078] In a theatre or other large volume application, it is
cumbersome to stock different sized glasses. As an optimization to
the curved glasses it is possible to incorporate a feature into the
design of the frame of the glasses that automatically adjusts a
dihedral angle between the curved lenses to accommodate wider and
narrower interpupillary spacing. Adjusting the dihedral angle
insures a close to normal light incidence when viewing the screen
with a primary gaze. This adjustment is done by exploiting the
flexibility and bending strength properties of molded thermoplastic
frames, or other frames having similar properties of strength and
flexibility (e.g., metals, fiberglass, composites, etc).
[0079] In this design there is an outward convexity to the shape of
the frames, which creates a dihedral angle between the lenses. In
one embodiment, the bridge of the glasses is designed to flex
slightly with head size variation due to pressure on the frame
(e.g., pressure exerted on the temple portion of the frames). This
flexing results in dihedral angle changes. As shown in FIG. 8B,
wider heads 875 with (statistically) larger interpupillary spacing
have a larger dihedral angle O.sub.A. In this context, the dihedral
angle is defined as the angle between a planes extending through
endpoints on opposite ends of the lenses (see dashed line in FIG.
8B). Smaller heads 880 would have a smaller dihedral angle
.theta..sub.B. With a smaller head and corresponding smaller
dihedral angle between the lenses, the distance between the forward
directed radii of the curved lenses is reduced to more closely
match the smaller interpupillary spacing.
[0080] FIG. 9 illustrates both cases. Glasses 900 are illustrated
in a first position 900A as when worn by an adult with a relatively
larger sized head. Interpupillary spacing of the adult is
represented by Y. A temple or "around the ear" portion of the frame
of the glasses have a spacing represented by Y' to accommodate the
adult's head size, causing a flex of the bridge 910 of the glasses
and resulting in a larger dihedral angle between the lenses.
[0081] Position 900B, is similar to that when worn by a child with
a relatively smaller sized head, and the interpupillary distance of
the child is represented by X. The bridge 910 is less flexed
because the temple or "around the ear" spacing is reduced to X'
which results in a smaller dihedral angle between the lenses. The
smaller dihedral angle accommodates the child's smaller
interpupillary spacing as described above.
[0082] FIG. 10 illustrates details for the lenses. At 1005, an
adult right eye pupil 1010A is shown relative to a child's eye
pupil 1015A), with the lens 1020 having a center of curvature at
1025A. As seen in FIG. 10, comparing the position of lens 1020 to
lens 1030 in position 1030A, a larger dihedral exists between the
lenses. This is the appropriate lens configuration for an
adult.
[0083] When worn by a child (or person with a relatively smaller
sized head), an amount of flex of the bridge of the glasses cause
lenses 1030 and 1020 to decrease in dihedral as illustrated by 1050
for the left eye (consistent with FIG. 9, a similar dihedral
decrease (not shown) occurs for the right eye in lens 1020). The
center of the radius of curvature (1040 for lens 1030 in position
1030B) has shifted from an alignment corresponding to the adult
pupil 1010B to an alignment corresponding to the child's pupil
1015B.
[0084] FIGS. 8B, 9, and 10 are illustrative of an accommodation for
both "adult sized" and "child sized" heads and interpupillary
distances. However, it should be understood that interpupillary
distances and head sizes vary amongst the entire population. While
near perfect alignment may occur for some viewers, it is not
required and the embodiments illustrated function to accommodate
the varying head sizes and interpupillary distances by improving
the viewing angle alignments in most cases.
[0085] The lenses shown in FIG. 10 have a 50 mm radius of curvature
and the dihedral angle is 2 degrees. With conventional sized frames
the dihedral angle change for the average adult verses child is
about 5 degrees (approximately 2.5 degrees accounted for on each
side of the frames for a total of about 5 degrees). This technique
works best with lenses with a radius of curvature that is about
half the length of the temple portion of the glasses.
[0086] As noted above, the present invention addresses some of the
problems with the Spectral Separation method for projecting 3D
images, specifically an improvement in the efficiency, increase in
the color gamut, and a reduction in the amount of color
compensation required. In some cases, the color compensation may
not be required.
[0087] Referring again to the drawings, and more particularly to
FIG. 11 thereof, there is illustrated a set of left and right
spectral separation filters representative of those currently used
in D-Cinema 3-Dimensional (3D) presentations. As shown in FIG. 11,
the conventional spectral separation filters provide three
primaries for each eye by dividing the red, green, and blue color
channels of a projector into two sets of primaries, one set for the
left eye (primaries 1110R, 110G, and 110B) and one set for the
right eye (primaries 1112R, 1112G, and 1112B). For example, the
left eye is illustrated as having shorter wavelength blue, green,
and red bands than the right eye. Following a conventional design,
the left eye may have, for example, passband wavelengths of
approximately 400 to 445 (blue), 505 to 525 (green), and 595 to 635
(red). The right eye may have, for example, passband wavelengths of
approximately 455 to 495 (blue), 535 to 585 (green), and 645 to 700
(red).
[0088] While a filter configuration like that illustrated in FIG.
11 provides all three colors to each eye, the resulting image has a
somewhat different hue in each eye. In order to make the images
more closely match the colors for each eye, and match the colors in
the original image, color correction is applied. The color
correction reduces the overall efficiency of the system (since it
boosts some primaries preferentially over others). In addition,
even with color correction, the new left and right primaries do not
have as large of a color space as the projector, and thus can only
produce a portion, but not every color that would be present if
projected without the filters in a 2D system.
[0089] FIG. 12 is a 1931 CIE chromaticity diagram illustrating the
unfiltered color space 1200 and P3 white point 1210 of a typical
Digital Cinema (D-Cinema) projector. The unfiltered color space of
the projector represents the color space available for projecting
images.
[0090] FIG. 13 is a 1931 CIE chromaticity diagram illustrating the
color space of conventional spectral separation filters used to
separate the left eye channel 1320 and right eye channel 1330 in a
D-Cinema projector. The intersection of the left and right eye
channel color spaces represents the potential color space of images
projected through the filters. As can be seen in FIG. 13, the
potential color space using the conventional filters is restricted
compared with the projector color space (1200, FIG. 2). In
addition, the P3 white point 1310 is an important factor in the
overall result of the projected image, and is significantly shifted
compared to that of the projector alone--see P3 white point 1315
for the left eye and P3 white point 1325 for the right eye and
compare to projector P3 white point 1210, shown for reference in
FIG. 13.
[0091] The present invention pertains to the filter installed in
the projector, which is the main controlling factor in the color
space of the system. The invention addresses both the efficiency
and the color space issues by splitting at least one of the
projector primaries into subparts. In one embodiment, the blue and
green projector primaries are split into three sub-parts each. The
exact wavelengths of where the primary is split may be chosen in
any manner that takes into account the particular color space to be
reproduced.
[0092] For example, as shown in FIG. 14, in one potential
configuration, a right channel projection filter has passband
wavelengths of blue at 400 to 440 (410-B1) and 484 to 498 nm
(410-B2), green at 514 to 528 (1410-G1) and 567 to 581 nm
(1410-G2), and red at 610 to 623 nm (1410-R). A left channel
projection filter has passbands wavelengths of blue at 455 to 471
nm (1412-B), green at 539 to 556 nm (1412-G), and red at 634 to 700
nm (1412-R). Of course other permutations exist, such as, for
example, switching the left and right channel wavelengths, or
switching the green and blue wavelengths etc. In addition, the
passband wavelengths are approximate and each band may vary by, for
example +/-5 nm or more. Such variations may occur by shifting the
entire passband and/or by selecting one or more different endpoints
for the passbands. An important consideration is that such
variances should not reduce the guard band between passbands to a
level where a system using the filters incurs unacceptable levels
of crosstalk between the channels.
[0093] The selection of passband wavelengths is made such that when
an image is projected with a D-Cinema projector with a P3 white
point 1210 and color space 1200 as, for example, shown in FIG. 12,
the resultant color space in the channels, and more particularly
the combined color spaces of the projected images, have a color
space and white point that more closely match the color space 1200
and P3 white point 1210 compared to the color space and white point
that occurs when using conventional spectral separation, such as
shown in FIG. 13. The passbands are also chosen to maximize
efficiency by selecting passbands that will result in having
approximately the same, or balanced, luminance levels in each
channel. So long as sufficient bandwidth is available in each
passband to achieve the stated improvements (as, for example,
proven by experimental results), there are no theoretical limits on
the variances that may occur over the example passband wavelengths
described herein.
[0094] Note that there are gaps in the spectrum of colors that did
not exist in the previous design (for example between 498 nm and
514 nm for blue to green transition in the right channel, and
between 581 nm and 610 nm for the green to red transition in the
right channel). These notches are designed to increase the color
space so that it matches the P3 color space in D-Cinema projectors.
The filter response needed to get the correct P3 result was derived
using the real (measured) spectral response from the D-Cinema
projectors, which is reflected in the chosen wavelengths for the
passbands described above.
[0095] Also note that in the illustrated example, the three
sub-parts are structured such that they are interleaved between the
right and left channels. From a practical standpoint, this means
that the three sub-parts are arranged such that one filter has at
least one sub-part lower and one sub-part higher than the sub-part
of the other filter. For example, in FIG. 14, the blue passbands of
the right channel projection filter straddle the blue passband of
the left channel projection filter. Such interleaving is preferably
maintained in the various embodiments, including those embodiments
that divide passbands into more than 3 sub-parts. Although
theoretically there is no limit on the number of sub-parts in which
any passband may be divided, due to cost and other factors, a point
of diminishing returns is quickly reached and 3 sub-parts each of
blue and green and 2 sub-parts of red appears to have the greatest
return with reasonable cost. With improved components and/or
reduced costs of components, a different economic analysis may
result and 4, 5, or more sub-parts, including additional sub-parts
in the red, may be justified for additional incremental increases
in the color space. Such incremental improvements might also be
justified under current economic and cost models for upper end
equipment markets.
[0096] FIG. 15 shows the color space diagrams for the filters of
this invention described above. As can be seen in FIG. 15, the
intersection, or product, of the left channel projection filter
color space and right channel projection filter color space results
in a color space more closely matching the color space 1200 (FIG.
12) than which occurs with conventional spectral separation. Some
portions of the color space are reduced and other portions of the
color space are increased. Although some areas of the color space
are reduced, the reduced areas are less important to viewers. Areas
of the color space to which viewers are more sensitive have made
significant gains with the invention versus conventional spectral
separation.
[0097] Glasses used to view the projected images need not be as
complex as the projector filter since the notches that provide the
improved color space have no impact on the left/right eye (or
left/right channel) separation, and therefore the notches do not
need to be reproduced in the viewing filters of the glasses (the
projector filter has more bands, and therefore more complexity than
the viewing filters). As shown in FIG. 16, in one configuration the
right eye lens of the glasses would have a filter with passband
wavelengths of approximately 430 to 440 nm (part of the blue band),
484 to 528 nm (part of the blue, and part of the green band), 568
to 623 (part of the green band and the red band), which encompass
the passbands of the right channel projector filter. The left eye
lens of the glasses would have a filter with passband wavelengths
of 455 to 471 (blue), 539 to 555 nm (green), and 634 to 700 nm
(red) which encompass the passbands of the left channel projector
filter. Wavelengths below the beginning wavelengths in the blue
(approximately 430 nm) and wavelengths above ending wavelengths in
red (approximately 700 nm) are beyond the visible spectrum and may
either be included or excluded from the passbands. Other
permutations exist as described before (including left/right
channel exchange), but the left and right eye lenses of the glasses
include corresponding permutations that encompass or match the left
and right channel projector filter permutations.
[0098] Along with other factors such as projector color space and
white point, the final images viewed through the glasses are a
product of the projecting filters and viewing filters (e.g.,
filters in the glasses used to view the images). In the described
embodiments, the receiving filters are less demanding as far as
passband design because they have fewer notches and they generally
encompass more wavelengths in at least some of the passbands. The
important role played by the glasses is separation of the entire
images as whole and as projected, not specific bands within each
image as described for the projection filters.
[0099] The overall response (color space and white point) to the
eye is the product of the spectral response of the projector
filter(s), the lenses/filters of the eyeglasses, and the base
D-Cinema projector response (color space and white point of the
D-Cinema projector without the left and right channel projector
filters). Nevertheless, the color space is mostly defined by the
position of the passbands and the notches in the yellow and
blue-green bands, and therefore the overall response is mostly a
function of the projector filter (because the glasses do not need
and preferably do not have the notches).
[0100] In part, because of the lower complexity of the eyeglass (or
viewing) filters, the eyeglass filters are also comparatively less
expensive to produce compared to the projection filters. This is a
benefit because the eyeglass filters are generally embodied as a
pair of glasses worn by viewers (including the general public), and
are therefore likely to be subjected to less than perfect care,
whereas the projector equipment including the projector filters are
generally kept in more secure and stable environments. In addition,
the glasses are generally purchased in larger numbers than the
projector filter(s).
[0101] Another aspect of the differing complexities of the eyeglass
(or viewing) filters compared to the projector filters is that they
create an asymmetric filtering system. That is, each viewing filter
and its corresponding projection filter of the same channel are not
symmetric in bandwidth and/or the number of passbands. The
passbands of the viewing filters may also entirely encompass the
passbands of the projection filters (and, in some embodiments, the
passbands of the projector filter may be blue-shifted relative to
the passbands of the viewing filters to account for viewing angle
related blue shifts in the viewing filters). Regardless of whether
the projection filters are entirely encompassed by the passbands of
the viewing filters, the passbands of the viewing and projection
filters preferably are different. Therefore, a preferred result is
an asymmetric filtering system.
[0102] The particular projector filter response used in describing
the invention uses 3 divisions of the blue and green projector
color bands. The red band is divided into two parts (one part for
the right channel and one part for the left channel). Additional
divisions may be utilized for increased color space, but additional
cost of the filters may be incurred. Careful selection of the
optical passbands provides a close match to the color space and
white point of the original unfiltered projector. The design of the
glasses is such they have the same complexity of the conventional
spectral separation design, but provide adequate selectivity to
minimize crosstalk between the images projected in the left and
right channels.
[0103] FIG. 17A is a block diagram of a projection system 1700
according to an embodiment of the present invention. The projection
system 1700 includes a digital cinema projector 1705 that projects
spectrally separated 3D images (a left channel image and a right
channel image) through projection filter 1730 and projection lens
1720 onto a screen 1710 for viewing with glasses 1715. Glasses 1715
include, for example spectrally separated filters disposed as
coatings on each lens of the glasses such that the right lens
comprises a filter that matches or encompasses the passbands of the
right channel filter and the left lens comprises a filter that
matches or encompasses passbands of the left channel filter (each
of the left and right channel images are intended to be viewed by a
viewer's corresponding left or right eye through the corresponding
left or right eye lens/filter of the glasses). The glasses 1715,
and system 1700, may, for example, include any of the features,
systems, or devices described in Richards et al., a U.S. patent
application entitled METHOD AND SYSTEM FOR SHAPED GLASSES AND
VIEWING 3D IMAGES, Ser. No. 11/801,574, filed May 9, 2007, the
contents of which are incorporated herein by reference as if
specifically set forth.
[0104] The projector 1705 receives image data for projection from a
server 1780. 3D content is provided to the server 1780 from, for
example, a disk drive 1740. Alternatively, 3D content may be
transmitted to projector 1705 over a secure link of network 1755
from, for example, an image warehouse or studio 1750. Multiple
other projectors (e.g., at theaters around the globe, 1760.sub.1 .
. . 1760.sub.n) may also feed from similar network or other
electronic or wireless connections including wireless networks,
satellite transmission, or quality airwave broadcasts (e.g., High
Definition or better broadcast).
[0105] The server 1780 includes color correction module 1775 that
performs mathematical transformations of color to be reproduced by
the projector prior to image projection. The mathematical
transformations utilize image data for each of the left and right
channels and transform them into parameters consistent with the
primary colors or passbands of the corresponding left or right
channel filter. The mathematical transformation, or color
corrections, adjust the hue of each image and maximize the
available color space and match the color space and white point of
projector 1705 as closely as possible. The amount of color
correction required when using the invention is significantly
reduced when compared with conventional spectral separation.
[0106] The color corrected 3D content is transmitted to projector
1705. The 3D content includes left and right channel images that
switch at a rate fast enough that they blend into a single 3D image
when viewed by a viewer through glasses 1715. At some point in the
optical path of the projection system, filters according to the
present invention are utilized. For example, a filter wheel 1730 is
placed at point in the optical path closer to the light source.
FIG. 17B provides an illustrative example of a filter wheel 1730 in
front, side, and angle views. Specifications for appropriate
physical dimensions and characteristics of the exemplary filter
wheel 1730 include, for example: an outside diameter (OD) 1732 of
125.00 mm+/-0.15 mm, an inside hole 1734 with a diameter (ID) of
15.08 mm+/-0.04 mm (that is, for example, off-center by not more
than 0.075 mm), and a thickness of 1.00 mm-1.20 mm. The exemplary
filter wheel includes, for example, Material: Borofloat or Fused
Silica, Monolithic Filter, 2 Section (e.g., TYPE A, a first channel
filter, and TYPE B, a second channel filter), Max 3 mm Undefined
Transition, Clear Aperature: 1 mm From OD, 10 mm From ID, Surface
Quality: 80-50 Where Scratch Number Is Width Measured In Microns,
Edge Finish: As Fabricated, Edge Chips: Less Than Or Equal To 1 mm.
All such specifications are exemplary and other combinations of
materials, dimensions, and/or construction techniques, etc, may be
utilized. Alternatively, an electronically switched filter 1725 is
placed, for example, after the projection lens 1720.
[0107] A controller 1735 provides signals that maintain
synchronization between the filter 1730 and the image being
projected. For example, features of a left channel filter according
to the present invention are active when a left channel image is
being projected, and features of a right channel filter according
to the present invention are active when a right channel image is
being projected. In the electronically switched filter case, the
controller signals switching between left and right channel filters
in synchronicity with the left and right image projections. In the
filter wheel embodiment, for example, the controller maintains a
rotational speed and synchronicity between the left and right
channel images and the left and right channel filters respectively.
The blended image as viewed through glasses 1710 has a color space
and white point that closely matches a color space and white point
of projector 1705 without filter 1730.
[0108] The present invention includes an embodiment in which a
filter wheel having left and right channel projection filters
disposed thereon is placed inside a movie projector between the
light source and integrating rod of the movie projector. The
advantage of this placement is that the amount of light passing
through the remaining optical components is reduced and less likely
to overload sensitive electronics or other components (e.g. DLP,
LCOS, or other light processors or light valves in the projector),
but the amount of light that exits the projection is system is
equivalent to embodiments where the projection filter(s) is placed
further downstream locations. Alternatively, the power of the light
source can be increased resulting in increased output without
jeopardizing the integrating rod or other downstream
components.
[0109] Further advantages to the described placement of the filter
is that the filter can be made smaller than at most other points in
the light patch, and at a reduced cost compared to larger filters.
And, images formed after filtering are generally found to be
sharper than images formed and then filtered.
[0110] In one embodiment, the projection filter is a filter wheel
where approximately 1/2 the wheel has filter characteristics of a
left channel filter according to the present invention and
approximately 1/2 A the wheel has filter characteristics of a right
channel filter according to the present invention. Table 1
specifies an exemplary filter wheel specification for a multi-band
filter having a left channel filter section and right channel
filter section. The Delta values shown in Table 1 specify a slope
(steepness) of the band edges. The T50 values specify the
wavelength at the band edge where the light transmission is 50%. At
the band pass wavelengths the transmission is at least 90%, and at
the band reject wavelengths the transmission is less than 0.5%. The
wheel may have, for example a diameter of approximately 125 mm
diameter which is well suited for installation in a D-Cinema
projector (e.g., projector 705) between the light source and
integrating rod.
TABLE-US-00001 TABLE 1 Exemplary Filter Wheel Specification Delta
T.sub.0.5 Delta T.sub.90 Right Left T = 0.5% T = 90% T = 50% T =
50% -- -- .uparw.<430 nm <8 nm <2 nm .dwnarw.440 nm +- 2
nm <8 nm <2 nm .uparw.456 nm +- 2 nm <8 nm <2 nm
.dwnarw.470 nm +- 2.5 nm <8 nm <2.5 nm .uparw.484 nm +- 2.5
nm <10 nm <3 nm .dwnarw.498 nm +- 3 nm <10 nm <3 nm
.uparw.511 nm +- 3 nm <10 nm <2.5 nm .dwnarw.526 nm +- 2.5 nm
<10 nm <2.5 nm .uparw.538 nm +- 2.5 nm <10 nm <3 nm
.dwnarw.554 nm +- 2.5 nm <10 nm <3 nm .uparw.568 nm +- 2.5 nm
<12 nm <3 nm .dwnarw.584 nm +- 3 nm <12 nm <3 nm
.uparw.610 nm +- 3 nm <12 nm <3 nm .dwnarw.621 nm +- 3 nm
<12 nm <3 nm .uparw.635 nm +- 3 nm -- -- .dwnarw.>690
nm
[0111] The above exemplary specifications include some
pre-blue-shifting consistent with the above-cited Richards et al
patent application. However, inclusion of blue-shifting and other
features is not required.
[0112] Table 2 specifies an exemplary set of viewing filters
matching (or encompassing the passbands of the projector filters
but also including a small amount of red shift). The filters
include a multi-band filter for the left channel (or left eye lens)
and a multi-band filter for the right channel (or right eye lens).
The Delta values specify the slope (steepness) of the band edges.
The T50 values specify the wavelength at the band edge where the
light transmission is 50%. At the band pass wavelengths the
transmission is at least 90%, and at the band reject wavelengths
the transmission is less than 0.5%. These filters are, for example,
placed on left and right lenses of glasses 1715.
TABLE-US-00002 TABLE 2 Exemplary Viewing Filters Delta T.sub.0.5
Delta T.sub.90 Right Left T = 0.5% T = 90% T = 50% T = 50% -- --
.uparw.<430 nm <12 nm <3 nm .dwnarw.442 nm +- 3 nm <12
nm <3 nm .uparw.458 nm +- 3 nm <12 nm <3 nm .dwnarw.472 nm
+- 3 nm <16 nm <4 nm .uparw.486 nm +- 3 nm <16 nm <4 nm
.dwnarw.528 nm +- 3 nm <16 nm <4 nm .uparw.540 nm +- 3 nm
<16 nm <4 nm .dwnarw.557 nm +- 3 nm <20 nm <5 nm
.uparw.571 nm +- 3 nm <22 nm <6 nm .dwnarw.624 nm +- 4 nm
<23 nm <6 nm .uparw.637 nm +- 5 nm -- -- .dwnarw.>700
nm
[0113] FIG. 18 is a drawing of a fixed filter arrangement in a two
projector system 1800 according to an embodiment of the present
invention. Left and right channel images are derived, decoded,
retrieved, or reconstructed from data stored on disk drive 1840 (or
received from an appropriate network or transmission reception) by
server 1880. Color correction as described above may also be
applied (not shown).
[0114] The decoded, color corrected (if applicable), left and right
channel images are then projected simultaneously from left and
right channel projectors 1805A and 1805B onto screen 1810 for
viewing through glasses 1715. A right channel filter 1820A having
passband characteristics as described above is used to filter the
projected right channel image. A left channel filter 1820B having
passband characteristics as described above is used to filter the
projected left channel image. The right and left channel filters
are fixed filters (e.g., filters with characteristics that do not
change with time), and are constructed, for example, from a clear
substrate (e.g., glass) coated with appropriate layers to produce
the passbands for the desired left or right channel filter
characteristics. The fixed filter may be located in the projector
at any point in the optical path, or may be located outside the
projector past the projection lens as shown in FIG. 18.
[0115] Although the present invention has been mainly described as
increasing color space by increasing the number of passbands in the
blue and green wavelengths (and interleaving those passbands
between the left and right channels), the invention should not be
limited to increasing the number of passbands in the same number or
in the same wavelengths as specifically described herein, and,
should include any number of increased passbands at any wavelength
capable of being passed by the projection filter. For example,
instead of dividing the blue primary into three sub-parts (2
subparts in one channel and one part in the other channel); the
blue primary may be divided into four or more sub-parts (e.g., 3
sub-parts in one channel and 2 sub-parts in the other channel).
Further, division of sub-parts as described herein may be performed
at any of the available wavelengths and can therefore be extended
into the red wavelengths. Further yet, discussion above should not
be viewed to limit implementations of wherein the additional
sub-parts of the blue and green bands are necessarily in the same
channel, as the invention can be practiced by having two sub-parts
of blue in a first channel, one sub-part of blue in a second
channel, two sub-parts of green in the second channel, and one
sub-part of green in the first channel. The same also logically
extends to embodiments with more than three sub-parts where the
additional subparts may be in any of the color bands and any of the
channels.
[0116] In yet another example, the recitations regarding curved
glass lenses having a 50 mm radius of curvature is exemplary and
any other radii could be utilized so long as the radius does not
extend toward infinity (making the glasses flat, or essentially
flat). For example a 40 mm radius or an 80 mm radius or more (e.g.,
even up to 200 mm) may provide suitable alternatives and not
detract an unacceptable amount from the benefits of the described
50 mm radius of curvature. In one embodiment, a radius of curvature
of the glass lenses is 90 mm (alternatively, approximately 90 mm)
which represents an acceptable trade-off considering the cost and
difficulty of coating lenses with a greater amount of curvature
without detracting too substantially from the benefits of optimally
curved lenses.
[0117] Various non-limiting and exemplary embodiments of the
invention are now described, including, for example, viewing
glasses comprising a non-flat substrate (e.g., non-flat lenses),
with spectrally complementary filters (alternatively, the filters
are for two channels such that the filter of a first channel passes
light bands of the first channel and blocks light bands of the
second channel and visa-versa). The viewing glasses may comprise,
for example, a first lens having a first spectral filter, and a
second lens having a second spectral filter complementary to the
first spectral filter, and the first and second lenses are each
curved to reduce a wavelength shift that occurs when viewing an
image at other than a normal angle through the lens. In various
embodiments, the curve of each lens comprises, for example, any of:
a radius centered on the viewers pupil, a radius centered behind
the viewers pupil, a non-spherical shape, a cylindrical shape,
includes multiple radii, a predetermined mathematical function,
prescription curvatures. In one embodiment, the spectral filters
have a thickness that varies by location on the lens. In another
embodiment, the spectral filters comprise a plurality of dielectric
layers, and the dielectric layers have an increased layer thickness
toward edges of the lenses.
[0118] In another embodiment, the present invention comprises
viewing filters comprising a non-flat substrate and spectrally
complementary filters. In one embodiment, at least one of the
spectrally complimentary filters comprises, for example, a single
passband configured to pass two lightbands of different colors. In
one embodiment, at least one of the spectrally complimentary
filters comprises a single passband configured to pass two
different colors of light. In one embodiment, the spectrally
complimentary filters are configured for viewing a 3D display,
which, for example, may comprise a reflection off a cinema screen.
In one embodiment, the spectrally complimentary filters comprise,
for example, a first filter having a set of primary passbands
comprising, a first passband configured to pass both a green
lightband and a red lightband, and a second passband configured to
pass both a blue lightband and a green lightband. In one
embodiment, the spectrally complimentary filters comprise, a first
filter comprising a first set of primary passbands comprising a
passband configured to pass both a green lightband and a red
lightband, and a second filter comprising a second set of primary
passbands comprising a passband configured to pass both a blue
lightband and a green lightband. In one embodiment, the spectrally
complimentary filters comprise a first filter having a set of 3
passbands configured to pass a set of more than 3 primary color
lightbands. In one embodiment, the spectrally complimentary filters
comprise a first filter comprising a first set of passbands
configured to pass a first set of primary lightbands and a second
filter comprising a second set of passbands configured to pass a
second set of primary lightbands, wherein the first set of primary
lightbands are mutually exclusive to the second set of primary
lightbands. Additionally, the first set of passbands and the second
set of passbands may be, for example, separated by guard bands
having a width calculated to maintain separation between the
primary lightbands when viewed through the viewing filters and
compensate for blue shift due to a viewing angle of the primary
lightbands through the viewing filters. In one embodiment, at least
one of the passbands encompasses at least two of the primary
lightbands.
[0119] In another embodiment, the invention comprises spectral
separation viewing glasses, comprising, a first lens comprising a
first spectral filter, and a second lens comprising a second
spectral filter complementary to the first spectral filter, wherein
the first spectral filter and the second spectral filter have at
least one guard band between adjacent portions of spectrum of the
spectral filters, and the guard band bandwidth is calculated based
on an amount of blue shift occurring when viewing portions of the
spectrally separated images at an angle through the lenses. In one
embodiment, the guard band has a bandwidth sufficient to reduce
crosstalk of spectrally separated images viewed through the
glasses. The guard band comprises, for example, approximately 2% or
more of a wavelength of a crossover point of adjacent portions of
the spectral filters.
[0120] In another embodiment, the invention comprises a spectral
separation viewing system, comprising. viewing glasses, comprising
a first lens having a first spectral filter, and a second lens
having a second spectral filter complementary to the first spectral
filter, wherein the spectral filters include a guard band between
adjacent portions of spectrum of the first and second lenses, and
the lenses have a curvature configured to cause angles of incidence
of light at edges of the lenses to be closer to normal when
compared to flat lenses. The curvature of the lenses are, for
example, spherical. In one embodiment, the spectral filters are not
uniform across the lenses. In various other embodiments, the
viewing system further comprises, for example, a projection system
configured to project first and second spectrally separated images,
and the first and second spectrally separated images are each
respectively viewed through the spectral filters of the viewing
glasses. The viewing system may also further comprise, for example,
a plurality of pairs of said viewing glasses, each pair of viewing
glasses being assigned to an individual viewer in a movie theater
audience, and the first and second filters are disposed on lenses
of each pair of glasses.
[0121] In yet another embodiment, the invention comprises a method,
comprising the steps of, projecting first and second spectrally
separated images onto a display screen, viewing the projected
images through a pair of glasses having a first lens having a first
spectral filter designed to be used with the first spectrally
separated image and a second lens having a second spectral filter
designed to be used with the second spectrally separated image, and
wherein the spectral filters are configured to have an amount of
wavelength shift effect depending upon a viewing angle through the
lens. In one embodiment, adjacent portions of spectrum of the first
and second spectral filters are separated by a guard band
comprising a bandwidth calculated for a central viewing location
and sufficient to eliminate crosstalk for normal viewing from edges
of the display screen. In yet another embodiment, the spectral
filters comprise a plurality of guard bands each separating a
different set of adjacent spectrums in the first and second
filters, and a bandwidth of each guard band is determined based on
a function of a crossover wavelength of the adjacent spectrums and
a viewing angle to an edge of the display screen. The display
screen is, for example, a cinema movie screen.
[0122] In yet another embodiment, the present invention comprises a
3D viewing system, comprising means for projecting spectrally
separated images, means for viewing the spectrally separated images
through different ocular channels, and means for compensating for
wavelength shifts occurring due to viewing angles to portions of
the images. In one embodiment, the means for compensating includes,
for example, means for adjusting an amount of spectral filtering
performed based on viewing angle. In another embodiment, the means
for compensating includes, for example, means for producing a
wavelength mismatch between projector filters used to project the
spectrally separated images and eye filters used to view the
spectrally separated images, wherein the mismatch compensates for
an amount of wavelength shift that occurs in the eye filters due to
light incident upon the eye filters at non-normal angles.
[0123] In yet another embodiment, the present invention comprises a
viewing system, comprising shaped glasses comprising a pair of left
and right spectrally complementary filters respectively disposed on
left and right curved lenses of the glasses, and a display system
configured to display spectrally separated left and right images
respectively configured to be viewed through the left and right
complimentary filters, wherein each spectrally separated image
comprises at least one light bandwidth approximately matching at
least one pass band of its corresponding filter. The display system
further comprises, for example, a projector configured to display
the spectrally separated left and right images with a
pre-determined amount of pre-blue shift. In one embodiment, the
spectrally complementary filters comprise guard bands between
adjacent spectrums of the spectrally complementary filters. The
shaped glasses of the viewing system, are, for example, utilized to
view color shifted projections of spectrally complementary images.
In one embodiment, the shaped glasses of the viewing system include
frame temples and a bridge designed to flex implementing an
adjustable dihedral angle between the lenses. An amount of the
dihedral angle change due to flexing is, for example, approximately
5 degrees.
[0124] In yet another embodiment, the present invention comprises a
method, comprising the steps of, distributing shaped glasses to
audience members; and projecting first and second spectrally
complementary images on a display screen within view of the
audience members, wherein the shaped glasses comprise first and
second shaped lenses having first and second spectrally
complementary filters respectively disposed thereon, and the first
and second spectrally complementary filters respectively correspond
in bandwidth to the projected first and second spectrally
complementary images. In one embodiment, the bandwidth
correspondence of the first spectrally complimentary filter passes
colors in a first channel of a projection and blocks colors in a
second channel of the projection, and the bandwidth correspondence
of the second spectrally complimentary filter passes colors in a
second channel of a projection and blocks colors in a first channel
of the projection.
[0125] In yet another embodiment, the present invention comprises a
storage medium having a visual performance stored thereon, that,
when loaded into a media player coupled to a display device, causes
the media player to transmit the visual performance for display to
the display device, wherein the visual performance comprises
spectrally separated images configured to be viewed respectively
through independent ocular channels using curved spectrally
separated filters. The storage medium is, for example, prepackaged
with at least one pair of glasses having curved lenses upon which
the curved spectrally separated filters are disposed. The
spectrally separated images are, for example, displayed by the
display device using filters that are blue shifted compared to
filtering that occurs through normal angle viewing of the curved
spectrally separated filters. The spectrally separated images are,
for example, separated by a guard band configured to compensate for
spectra mismatch between the projected images and properties of
filters used to view the projected images. The combination of
pre-blue shifting, curved lenses, and guard bands effectively
eliminates crosstalk when viewing the images.
[0126] In yet another embodiment, the present invention comprises,
for example, a system for viewing 3D images, comprising, serving 3D
content over a network to a receiving electronic device, projecting
the 3D content to a display device, wherein the 3D content
comprises spectrally complementary images intended to be viewed
with shaped glasses. The receiving electronic device comprises, for
example, a display system located at a movie theater. In one
embodiment, the projected 3D content is projected with a
predetermined amount of blue-shift.
[0127] In yet another embodiment, the present invention comprises a
method of displaying an 3-D image, comprising the steps of,
projecting left and right filtered images onto a screen, and
filtering the left and right images for each of spectrally specific
properties corresponding to the image prior to display on the
screen, wherein the filtering is performed with a filter having
characteristics that are shifted an amount configured to compensate
for a wavelength shift that occurs when a viewer watches the
screen. The wavelength shift comprises, for example, a blue-shift
that occurs due to viewing angles (which may be, for example, a
blue-shift that occurs in characteristics of an eye filter used to
view the images, or, as another example, a blue-shift occurring in
filtered viewing glasses when viewing any of the images through the
filtered viewing glasses at other than a normal angle). The
spectrally specific properties corresponding to the image comprise,
for example, a set of wavelengths corresponding to the right images
and a complimentary set of wavelengths corresponding to the left
images.
[0128] In yet another embodiment, the present invention comprises a
projector filter, comprising, a first filter having a first set of
primary passbands, and a second filter having a second set of
primary passbands, wherein the first set of primary passbands has a
different number of primary passbands than the second filter. In
one embodiment, the first filter has, for example, at least two
blue primary passbands and the second filter has at least one blue
primary passband. In another embodiment, the first filter has, for
example, at least two green primary passbands and the second filter
has at least one green primary. In another embodiment, the first
filter has, for example, two blue primaries and two green primaries
and the second filter has one blue primary and one green primary.
In another embodiment, the first filter has, for example, passband
wavelengths of approximately 400 to 440 nm and 484 to 498 nm, 514
to 528 nm, 567 to 581 nm, and 610 to 623 nm. The second filter has,
for example, passband wavelengths of approximately 455 to 471 nm,
539 to 556 nm, and 634 to 700 nm. The passband wavelength
specifications have a tolerance of, for example, approximately +-5
nm. In one embodiment, the primary passbands of the first filter
excludes wavelengths passed by the second filter. In one
embodiment, the primary passbands of the filters are selected to
maximize reproduction of a color space of a projector. The
projector color space is, for example, the color space of a
D-Cinema projector. In one embodiment, the projector filter is an
electronically switchable filter that switches between the first
and second filters according to an image synchronization
signal.
[0129] In yet another embodiment, the present invention comprises a
system for projection of spectrally separated 3D images,
comprising, a projection system configured to project left and
right channel images for display by a viewer, a filter placed in at
least one light path of the projection system comprising a left
channel filter and a right channel filter, wherein at least one of
the left and right channel filters has more than 3 primary
passbands. In one embodiment, one of the left and right channel
filters has at least 2 primary passbands in blue wavelengths. In
one embodiment, one of the left and right channel filters has at
least 2 primary passbands in green wavelengths. In one embodiment,
one of the left and right eye channel filters has at least 2
primary passbands in blue wavelengths and at least 2 primary
passbands in green wavelengths. In one embodiment, the primary
passbands of the filters are selected to maximize reproduction of a
color space of the projection system in images projected by the
projection system. In one embodiment, the system further comprises
a color correction module configured to color correct images
projected by the projection system according to a color space of
the filters. Alternatively, the color correction module is
configured to color correct images based on a color space of light
passed by the filter.
[0130] In yet another embodiment, the present invention comprises a
pair of projector spectral separation filters configured to divide
a blue projector primary into three sub-parts, a green projector
primary into three sub-parts, and a red projector primary into to
two sub-parts. One of the filters has, for example, two passbands
in blue, two passbands in green, and a single passband in red, and
the other filter has one passband in blue, one passband in green,
and one passband in red. In another embodiment, One of the filters
has, for example, two passbands in blue, two passbands in green,
and only one passband in red, and the other filter has only one
passband in blue, only one passband in green, and only one passband
in red. In one embodiment, one of the filters has, for example, two
passbands in blue, one passband in green, and one passband in red,
and the other filter has one passband in blue, two passbands in
green, and one passband in red. In another embodiment, one of the
filters has, for example, two passbands in blue, only one passband
in green, and only one passband in red, and the other filter has
only one passband in blue, two passbands in green, and only one
passband in red. In one embodiment, one of the filters has one
passband in blue, two passbands in green, and one passband in red,
and the other filter has two passbands in blue, one passband in
green, and one passband in red. In another embodiment, one of the
filters has only one passband in blue, two passbands in green, and
only one passband in red, and the other filter has two passbands in
blue, only one passband in green, and only one passband in red. In
one embodiment, the sub-part passbands are located to achieve a
substantial match to an original color space and white point of an
unfiltered D-Cinema projector.
[0131] In yet another embodiment, the present invention comprises,
for example, a set of color filters, comprising, a first filter
having a first set of primary color passbands, a second filter
having a second set of primary color passbands of different
wavelengths compared to the first set of primary colors, wherein
the first filter has more than one primary color in at least one
color band. The filter set is embodied, for example, as an
electronically switchable filter set. In one embodiment, the color
filter set is part of a 3D projection system and the primary
passbands of the first and second filters are selected to maximize
reproduction of a color space of the 3D projection system without
the first and second filters.
[0132] In yet another embodiment, the present invention comprises,
for example, a method, comprising the steps of, preparing a 3D
image comprising a left image and a right image, filtering the left
image with a left channel filter, filtering the right image with a
right channel filter, and projecting the left and right filtered
images onto a screen, wherein at least one of the left channel
filter and right channel filter have more than 3 primary passbands.
One of the left and right channel filters comprises, for example, 2
primary passbands in blue wavelengths and 2 primary passbands in
green wavelengths. In one embodiment, the method further comprises,
for example, a step of viewing the projected 3-D image through left
and right viewing filters having passbands that respectively
exclude passbands of the right channel filter and the left channel
filter. In another embodiment, the method further comprises, for
example, a step of switching the left and right channel filters in
synchronicity with the projection of left and right channel images
of the 3D image.
[0133] In yet another embodiment, the present invention comprises,
for example, a 3D viewing system comprising a first asymmetric
filter set comprising a projection filter and a viewing filter. In
one embodiment, the 3D viewing system may further comprise, for
example, a second asymmetric filter set wherein the first
asymmetric filter set is positioned in an optical path of the
system and configured to pass wavelengths of a first channel of the
system and the second filter set is configured to pass wavelengths
of a second channel of the system. In another embodiment, the
viewing filter includes passbands that encompass passbands of the
projection filter. In yet another embodiment, the viewing filter
includes, for example, passbands that approximately encompass
passbands of the projection filter; and the passbands of the
projection filter are blue-shifted compared to the passbands of the
viewing filter.
[0134] In yet another embodiment, the present invention comprises
an asymmetric filter system, comprising, a first set of filters
comprising a first set of optical passbands, a second set of
filters comprising a second set of optical passbands different from
the first set of optical passbands and encompassing the first set
of optical passbands. In one embodiment, the first set of filters
is upstream in an optical path relative to the second set of
filters. In another embodiment, the first set of filters comprise a
projection filter and the second set of filters comprise a viewing
filter. In another embodiment, the first set of optical passbands
comprises a right channel set of optical passbands and a left
channel set of optical passbands that exclude any portion of the
right channel set of optical passbands. In another embodiment, the
second set of optical passbands include a left channel set of
optical passbands and a right channel set of optical passbands that
exclude any portion of the left channel optical passbands.
[0135] In yet another embodiment, the present invention comprises a
method, comprising the steps of, providing a theater audience with
a pair of 3D viewing glasses comprising left and right lenses
respectively comprising left and right viewing filters, and
projecting left and right images onto a display screen using left
and right projection filters, wherein the left projection filter
and the left viewing filter comprise a first asymmetric filter set
and the right projection filter and the right viewing filter
comprise a second asymmetric filter set. In one embodiment, a total
number of passbands in the viewing filters is less than a total
number of passbands in the projection filters. In one embodiment,
the projector filters comprise passbands that divide blue light
wavelengths into at least three blue sub-parts and that divide
green wavelengths into at least two green sub-parts. In one
embodiment, a viewing filter in one of the asymmetric filter sets
comprises a passband that encompasses wavelengths in the longest
wavelength blue sub-part and wavelengths in a green sub-part. In
one embodiment, the projector filters comprise passbands that
divide green light wavelengths into at least three sub-parts and
divide red light into at least two red sub-parts, and a viewing
filter in one of the asymmetric filter sets comprises a passband
that encompasses a longest wavelength green sub-part and a red
sub-part. In one embodiment, the projector filters comprise
passbands that divide blue light wavelengths into at least three
sub-parts and green light wavelengths into at least three
sub-parts, and a viewing filter in one of the asymmetric filter
sets comprises a passband that encompasses a longest wavelength
blue sub-part and a shortest wavelength green sub-part. In one
embodiment, the projector filters comprise passbands that divide
green light wavelengths into at least three sub-parts and red light
wavelengths into at least three sub-parts, and a viewing filter in
one of the asymmetric filter sets comprises a passband that
encompasses a longest wavelength green sub-part and a shortest
wavelength red sub-part. In one embodiment, each viewing filter
comprises, three passbands exclusively comprising one passband
including blue wavelengths, one passband including green
wavelengths, and one passband including red wavelengths. In one
embodiment, the projector filters comprise 3 passbands each in
green and blue light wavelengths and two passbands in red
wavelengths. In one embodiment, the viewing filters each
exclusively comprises three passbands, one passband of blue
wavelengths, one passband of green wavelengths, and one passband of
red wavelengths. Other exemplary embodiments have been provided
throughout the present disclosure.
[0136] In yet another embodiment, the present invention comprises a
filter configurable in an eyewear device of a spectrally separated
3D viewing system, comprising a set of passbands and blocking bands
configured to pass light wherein at least one of the passbands is
capable of passing bands of 2 different colors of light and the
blocking bands are configured to block light in at least one band
of light in each of the 2 different colors. In one embodiment, the
passband capable of passing bands of 2 different colors of light
does not pass light in a third color. In one embodiment, the bands
of 2 different colors of light are separated by a notch. The notch
is, for example, a band (a notch band) not utilized by the 3D
viewing system for light transmission. In one embodiment, the notch
band is, for example, relatively narrow compared to the bands of 2
different colors of light. In another embodiment, the notch band
bandwidth is similar to a bandwidth of at least one of the bands of
2 different colors of light. In one embodiment, the notch band
encompasses a transition from wavelengths of a first of the 2
different colors of light to wavelengths of a second of the two
different colors of light. In one embodiment, the 2 different
colors of light comprise blue light and green light and the third
color comprises red. In one embodiment, the 2 different colors of
light comprise red light and green light and the third color
comprises blue. In one embodiment, the filter is disposed on a
curved substrate. In one embodiment, the filter is disposed on a
curved substrate having a radius of approximately 90 mm. In one
embodiment, the filter is disposed on a curved lens having a radius
of approximately 40 mm to 200 mm.
[0137] In one embodiment, the present invention comprises a filter
comprising only 3 mutually exclusive passbands of visible light, a
first passband configured to pass only a first color of light, a
second passband configured to pass 2 spectrum adjacent colors of
light comprising the first color of light and a second color of
light, and a third passband configured to pass 2 spectrum adjacent
colors of light comprising the second color of light and a third
color of light. In one embodiment, the first second and third
colors of light are, for example, blue, green, and red,
respectively. In another embodiment, the first, second, and third
colors of light are red, green, and blue, respectively. The filter
is, for example, disposed on a lens configurable as a channel
filter in a pair of 3D viewing glasses.
[0138] In describing the preferred embodiments of the present
invention illustrated in the drawings, specific terminology is
employed for the sake of clarity. However, the present invention is
not intended to be limited to the specific terminology so selected,
and it is to be understood that each specific element includes all
technical equivalents which operate in a similar manner.
[0139] For example, when describing a projector filter, any other
equivalent device or device having an equivalent function or
capability, whether or not listed herein, may be substituted
therewith. In another example, when describing a dielectric layer,
any other material used as filter and exhibiting a substantive
wavelength shift (e.g., nano-material coatings), whether used alone
or in combination with others so as to have an equivalent function
or capability, whether or not listed herein, may be substituted
therewith. In another example, a flexible bridge piece may be
substituted with any mechanism suitable to adjust a dihedral angle
of the lens, including a ratchet mechanism, spring loaded stops,
etc. In yet another example, lenses according to the present
invention may be constructed of glass, plastic, or any other such
material providing the appropriate shapes as described above.
[0140] Furthermore, the inventors recognize that newly developed
technologies not now known may also be substituted for the
described parts and still not depart from the scope of the present
invention. All other described items, including, but not limited to
lenses, layers, filters, wheels, screens, display devices,
passbands, coatings, glasses, controllers, projectors, display
screens, networks or other transmission capabilities, etc should
also be considered in light of any and all available
equivalents.
[0141] The present invention may suitably comprise, consist of, or
consist essentially of, any of element (the various parts or
features of the invention) and their equivalents as described
herein. Further, the present invention illustratively disclosed
herein may be practiced in the absence of any element, whether or
not specifically disclosed herein. Obviously, numerous
modifications and variations of the present invention are possible
in light of the above teachings. It is therefore to be understood
that within the scope of the appended claims, the invention may be
practiced otherwise than as specifically described herein.
[0142] Portions of the present invention may be conveniently
implemented using a conventional general purpose or a specialized
digital computer or microprocessor programmed according to the
teachings of the present disclosure, as will be apparent to those
skilled in the computer art (e.g., controlling an electronically
switched pre-blue shift projection filter).
[0143] The present invention includes a computer program product
which is a storage medium (media) that includes, but is not limited
to, any type of disk including floppy disks, mini disks (MD's),
optical discs, DVD, HD-DVD, Blue-ray, CD-ROMS, micro-drive, and
magneto-optical disks, ROMs, RAMs, EPROMs, EEPROMs, DRAMs, VRAMs,
flash memory devices (including flash cards, memory sticks),
magnetic or optical cards, SIM cards, MEMS, nanosystems (including
molecular memory ICs), RAID devices, remote data
storage/archive/warehousing, or any type of media or device
suitable for storing instructions and/or data. The present
invention includes software for controlling aspects of the present
invention including, for example, switching of pre-blue shifted
filters or performance of color correction stored on any computer
readable medium (media).
[0144] In addition, such media may include or exclusively contain
content prepared or ready for display according to the present
invention. Such content is, for example, read from the media and
then transmitted electronically over a network, broadcast over the
air, or transmitted by wire, cable or any other mechanism.
Ultimately, the content of such media may be provided to a display
device and then viewed in accordance with one or more aspects of
the invention. The content is, for example, prepared or optimized
so as to project images having bandwidths optimized for the display
and viewing processes described herein. Such media may also be
packaged with glasses and/or filters prepared according to one or
more of the various aspects of the invention as described
above.
[0145] The present invention may suitably comprise, consist of, or
consist essentially of, any of element (the various parts or
features of the invention, e.g., shaped lenses, varying dielectric
layer thicknesses, pre-shifting projected or displayed images,
etc., and/or any equivalents. Further, the present invention
illustratively disclosed herein may be practiced in the absence of
any element, whether or not specifically disclosed herein.
Obviously, numerous modifications and variations of the present
invention are possible in light of the above teachings. It is
therefore to be understood that within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described herein.
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